Tottenham manager Mauricio Pochettino confirmed Harry Kane has damaged ligaments in his ankle but no time frame has been put on his return.
Kane had to be carried off on a stretcher after scoring the winner against Sunderland on Sunday and the 23-year-old looks set for a lengthy spell on the sidelines.
Spurs insist a more accurate diagnosis is not possible due to swelling around Kane’s right foot but grade two ligament damage could put the forward out for six to eight weeks.
“He got a ligament ankle problem and we need to assess every day and see,” Pochettino said.
“Today it’s impossible to give a time for a recovery. I am not a doctor. I can only explain what the doctors said to me.
“He is in a very good mood. We chatted before in the restaurant, he’s in a very good way.
“There are different rumours, we cannot guess whether it’s eight weeks, 10, four, one. It’s impossible to assess today and know how long.”
Kane is almost certain to miss England’s World Cup qualifiers against Malta and Slovenia in three weeks’ time, as well as Champions League fixtures against CSKA Moscow next Tuesday and Bayer Leverkusen on October 18.
Spurs’ crunch north London derby against Arsenal on November 6, just under seven weeks away, may come too soon, while his involvement in England’s qualification game against Scotland on November 11 and their friendly at home to Spain four days later also appears in doubt.
Kane has endured an exhausting two years after he played all of Tottenham’s 38 Premier League games last season, in between consecutive summers representing England, first at under-21 level and then at Euro 2016.
Pochettino admitted the only positive was that his star man will now have some time to recuperate.
“We must take that. We need to be positive now the damage is done,” Pochettino said.
“It’s a good opportunity to build his body, his fitness, his mentality and to work hard on different aspects and help him become more strong.”
Kane’s absence also hands an opportunity to summer signing Vincent Janssen, the Dutch striker brought in from AZ Alkmaar in a deal worth £18.5million in July.
Janssen scored 27 goals for AZ last season but is yet to open his account for his new club.
“Vincent arrives in a good moment – he’s ready to compete,” Pochettino said.
“You can see his qualities. It’s always difficult when you don’t have an opportunity to play – strikers are always excited to play and sometimes feel the pressure.
“Now he needs to be calm and he has an opportunity tomorrow to compete.”
Janssen is likely to start against Gillingham in the EFL Cup third round on Wednesday, with Pochettino expected to rest the majority of his regular first-team players at White Hart Lane.
Centre-back Cameron Carter-Vickers, midfielder Harry Winks and talented winger Marcus Edwards, all Spurs academy products, could be given chances to impress, along with Kieran Trippier, Joshua Onomah and Tom Carroll.
Mousa Dembele and Eric Dier are unlikely to be risked after they suffered cramp on Sunday while Danny Rose is still recovering from a hamstring problem.